<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="./jquery.js"></script>
</head>

<body>

    <button id="btn">click</button>
    <button id="btn1">click</button>
    <button id="btn2">click</button>
    <br>
    <textarea name="" id="text" cols="30" rows="10">
        biu 嘟嘟嘟嘟嘟
    </textarea>

    <select name="" id="sel1">
        <option value="1">妲己</option>
        <option value="2">王昭君</option>
        <option value="3">亚瑟</option>
        <option value="4">项羽</option>
        <option value="5">刘备</option>
    </select>
</body>
<script>
    $('#btn').click(function() {
        $('#text').text('哇，好神奇啊')
    });

    $('#btn1').click(function() {
        $('#text').html('btn1 实现了效果')
    });

    $('#btn2').click(function() {
        $('#text').val('嘀嘀嘀嗒嗒嗒哒哒')
    });

    //为select标签中的option 标签 选中 value值为 3 的值
    $('#sel1').val(3)
</script>

</html>